Document Annotation Tools: Annotation Classification Mechanisms

Document annotation tools have been widely used in technology-enhanced learning. Through these tools, students can associate annotations with fragments of documents, which enhances the thorough analysis of content and develops meta-reflective thinking. Likewise, annotation tools can facilitate collaborative annotation among students, as well as implement innovative interaction mechanisms. In addition, most tools provide mechanisms for classifying annotations. These mechanisms facilitate the subsequent retrieval of relevant annotations. Therefore, classification mechanisms are essential to facilitating the evaluation of work done by students, promoting collaborative work in annotation communities, etc. In addition, classification mechanisms help students better understand what they should annotate, implicitly guiding them during annotation activities. However, while there are multiple studies focusing on other aspects of annotation tools, the classification aspect has deserved only marginal attention in the literature. This work makes an exploratory study focused on this essential, although somewhat ignored, requirement. As a result, five main approaches to annotation classification are identified: absence of classification mechanisms, classification based on annotation modes, classification by predefined semantic categories, classification based on folksonomies, and classification based on ontologies.